 
 (define-layout-input-format :text
   [file]
+  (unsupported-operation "Not available.")
   (let [lines (partition-by #(second (re-matches #"^([^:]*): .*$" %))
                             (line-seq (reader file)))]
     (when-not (<= (count lines) 5)

    (illegal-argument "Cannot store layout in :text format which does "
                      "not come from a concept lattice."))
  (let [nodes       (vec (keys (positions layout))),
        node-number (comp inc (seq-positions nodes))]
    (with-out-writer file
      ;; Node
      (doseq [n nodes]


(add-layout-input-format :simple
                         (fn [rdr]
                           (= "conexp-clj simple" (read-line))))

(define-layout-output-format :simple
  [layout file]
